In this issue:

LAAS Benefits Analysis.....1

FAA LAAS and European

GBAS Working Group

Meeting..............................2

WAAS Performance

Improvements....................3

WAAS Program

Rebaselined.......................4

International WAAS Closer

to Operational Implementation....................................4

GPS/WAAS Procedures

Data Available on the

Web...................................5

WAAS BETA MMR

Contract Signed with

Rockwell............................5

Formation of the IPCT.......5

Survey Pilot Program-The

Teenage Years....................6

WAAS Bends But Does Not

Break.................................6

LAAS Benefits Analysis

by Kristi Foster, GPS TAC/ATO-W Navigation Services

The FAA has contracted with IBM Business Consulting Services to

provide an independent analysis that estimates the benefits attributable to the Local Area Augmentation System (LAAS) beyond those

provided by existing and planned navigation services. The benefits

analysis will provide information to support FAA executives in decisions regarding LAAS

development and deployment, and airlines and other industry participants in decisions to

deploy and equip with LAAS. The benefits analysis will establish a baseline for quantifying the overall value that LAAS adds to the National Airspace System, and provide a

fact-based account of the potential benefits of LAAS capabilities. The benefits analysis

time horizon is 20 years (2009 – 2028).

The LAAS benefits analysis scope includes the potential users of LAAS as major and

regional air carriers, cargo operators, corporate operators, and operators of general aviation aircraft (Alaska only). The applications of LAAS are as a precision guidance system

and a complement to other systems. LAAS operations include precision approach and

landing guidance, precision takeoff and departure guidance, terminal area navigation,

and surface navigation. The 120 airports included in the benefits analysis include airports associated with likely LAAS users, low rate initial production (LRIP) sites, FAA

Operational Evolution Plan (OEP) airports, current Category (CAT) II/III ILS airports,

and qualifier CAT II/IIII airports.

The LAAS benefits analysis team was formed to determine the baseline and assumptions

for IBM’s benefits assessment. The benefits team consists of key FAA offices and industry

participants from MITRE, and IBM. The benefits analysis is not a formal business case, as

IBM is only examining the benefits of LAAS. ASD will complete the cost portion. Initially, ASD completed an independent rough-order-of-magnitude, which concluded that

the FAA benefits of LAAS do not outweigh the costs associated with the program.

IBM and the FAA collaboratively developed a list of assumptions for IBM to use as a basis

for their analysis. In particular, it is important to note that IBM was instructed to perform

their analysis for two different scenarios: 1) assuming 0 percent WAAS equipage; and 2)

assuming 100 percent WAAS equipage, for all types of operators. These scenarios were

chosen to place bounds around the uncertainty associated with future decisions on WAAS

The SATNAV News SATNAV News is SATNAV News produced by the

Navigation Services (ATO-W) branch of

the Federal Aviation Administration

(FAA). This newsletter provides

information on the Wide Area

Augmentation System (WAAS) and the

Local Area Augmentation System

(LAAS), and initiatives associated with

the implementation of satellite

navigation into the National Airspace

System (NAS).
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equipage. Additionally, during the course of the analysis,

IBM intends to provide a sensitivity analysis on those assumptions with high uncertainty.

IBM will identify, describe, and quantify the efficiency and

safety benefits of LAAS CAT I and CAT II/III straight-in

approaches, complex procedures, and the use of LAAS as

an enabler of other technologies.

To date, the following milestones have been accomplished

for the LAAS benefits analysis:

! The establishment of the navigation capabilities

baseline was completed in November 2003

! A list of incremental capabilities that LAAS can

provide above the current baseline was completed in

December 2003

! IBM presented an analysis of preliminary findings of

the potential incremental benefits from LAAS in

February 2004

IBM has been working with representatives from industry

and several airlines during the development of the navigation baseline, LAAS capabilities, and preliminary findings.

IBM is currently consulting with five airlines and five airports that have previously demonstrated support for the

LAAS program to validate analysis findings performed to

date, and to understand current operations and how LAAS

may provide additional benefit to these operations. The

objective is to use data gathered during these visits to verify/

validate the methodology and mathematical formula IBM

is currently using to quantify benefits of LAAS. The airline

analysis will encompass airports relative to that particular

airline’s operations. The expected outcome is to make the

airlines and airports aware of the potential LAAS benefits

to their specific operation.

IBM will provide an update to the preliminary findings in

June 2004. The final LAAS Benefits Analysis Report is expected by October 2004.

This work continues to be an important milestone for the

LAAS program and is an essential part for the decision

making on how to proceed with the development and implementation of LAAS technology.

FAA LAAS and European

GBAS Working Group

Meeting

by Dieter Guenter, GPS TAC/ATO-W Navigation Services

In April, representatives from the Federal

Aviation Administration (FAA) Local

Area Augmentation System (LAAS) team

participated in a Ground Based Augmentation System (GBAS) working group meeting chaired by

EUROCONTROL at the Eurocontrol Technical Unit in

Bretigny, France. This European GBAS working group was

established several years ago as forum for the development

of GBAS technology, for the evaluation of GBAS benefits,

and for the development of a GBAS implementation strategy for Europe. In 2003, GBAS working group members

visited FAA headquarters and the FAA William J. Hughes

Technical Center in Atlantic City, New Jersey to exchange

information and to discuss approaches for cooperation.

Recently, as a result of the FAA decision earlier this year to

move LAAS to a research and development program, European service providers were prompted to re-evaluate their

GBAS activities. Representatives from the FAA’s LAAS team

agreed to provide a presentation on current LAAS plans and

activities at the April GBAS meeting to support Europe in

their re-evaluation of these plans.

Topics discussed included:

a. Current GBAS Category I activities of individual

service providers

b. Presentation and discussion of LAAS Category I

technical issues

c. Comparison of tools and processes

d. Presentation and discussion of Category II/III architectures/strategies

e. Presentation and comparison of the

EURONCONTROL GBAS business case and FAA

LAAS benefit case activities

f. Discussion of areas of cooperation.
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Overall, it was agreed that the GBAS working group and the

FAA LAAS team should continue their close coordination

and develop more detailed areas of cooperation. Many of the

present service providers have their national GBAS programs

aligned with the FAA program schedule and were planning

on LAAS being available in 2006. Changes in the FAA program will have an impact on European implementation efforts, so close coordination between the U.S. and Europe is

important. National representatives will be assessing the impact of recent FAA program decisions on their national GBAS

plans. Also, it was agreed to coordinate more closely on business case and benefits assessment methodologies and to exchange associated information. The next GBAS meeting is

planned for the end of the year, possibly in November, and is

considered an important meeting as future national and international GBAS plans/options will be discussed.

WAAS Performance

Improvements

by Ed Sigler, GPS TAC/ATO-W Navigation Services

The commissioning of the Federal Aviation Administration’s Wide Area Augmentation System (WAAS) in July 2003

provides aviation users with safe and

reliable satellite-based navigation for en-route and vertically

guided landing phases of flight. However, the FAA is not

resting on the laurels of achievement. Instead, the FAA is actively designing and developing towards Full Operational

Capability (FOC). These performance improvements will be

incrementally inserted into the operational WAAS starting

in early 2004. Planned performance improvements to the

WAAS will cover the breadth of the program and are intended

to increase the availability and reliability of the lateral navigation/vertical navigation, lateral precision with vertical guidance, and eventually global navigation satellite system landing system services throughout the national airspace system.

As the WAAS is an operational safety-of-life navigation system, all performance improvements are thoroughly analyzed

and tested prior to introduction into the operational system.

To further minimize risk, performance improvements are segmented into separate ‘builds’ that incrementally contribute

to the WAAS performance goals. Individual builds provide

for manageability and minimize operational system impacts.

The initial performance build, which began earlier this year,

will accomplish two goals: the replacement of selected equipment to increase system reliability and to demonstrate the

internal FAA processes and procedures for upgrading the

WAAS without performance degradation or safety impacts.

Additional performance builds will incrementally add enhanced ground processing algorithms that will provide 1)

reduced error bounding, 2) increased WAAS service availability, and 3) improved performance in geomagnetic storms.

Another performance build will provide increased bandwidth, reliability, and security for the WAAS backbone network. This network connects the WAAS ground receiving,

processing, and transmission elements. The addition of

WAAS reference stations in Alaska, Canada, and Mexico

will work in conjunction with the algorithm and network

performance builds to greatly increase the WAAS service area

in Alaska and provide for increased WAAS availability in

the Northeast and Southwest United States.

Performance builds will also provide for improved human

engineering of WAAS consoles for the FAA’s WAAS operators and maintainers via improved operator monitoring and

control screens, improved fault isolation procedures, and

increased reliability of equipment.

Finally, significant performance improvements to the WAAS

will be realized with the addition of two new geostationary

satellites transmitting the WAAS corrections and integrity

signal. Users generally can only see one geostationary satellite with our current geostationary satellite constellation. The

two new replacement geostationary satellites will significantly

increase the availability of the WAAS by providing users with

two satellites in view at all times over most of the WAAS

service area. The location of these satellites will also result

in improved WAAS coverage within Alaska. These satellites

and supporting satellite ground equipment are expected to

be integrated into the operational WAAS via separate performance builds in 2006.
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WAAS Program

Rebaselined

by Greg Thompson, GPS TAC/ATO-W Navigation Services

The WAAS Program recently completed

a rebaseline effort that culminated in

approval of continued WAAS development by the FAA’s Joint Resource Council (JRC) on May 3,

2004.

The last approved acquisition program baseline (APB) for

WAAS was developed in 1999. Much of the information in

the document was out of date and needed to be revised to

accurately reflect the current program direction. During

FY2005 budgetary formulation, the Office of Management

and Budget (OMB) requested that the WAAS program update this baseline.

Every part of the old baseline was reworked. This included

the system cost, schedule, performance, and benefits. While

developing the cost and schedule data, the decision was made

to extend the program baseline out until the year 2028. At

first glance, the overall cost seemed to go up. However, when

comparing the new baseline to the old baseline for the same

time period, the program costs actually went down approximately $500 million.

One of the good news stories of this whole effort was the

program benefit portion. An independent analysis of the program benefits determined that WAAS provided a positive cost

benefit ratio when considering benefits to aviation only. When

considering the recent explosion of WAAS receivers for nonaviation use, the benefits provided grows enormously. Some

estimates place the benefits derived from precision agriculture at over a billion dollars!

The new baseline covers development of WAAS to full GNSS

Landing System (GLS) capability, providing 200 foot minimums and three-quarter mile visibility through the use of dual

GPS frequencies. Implementation of GLS will be concurrent

with GPS modernization and is expected to occur in the 2013

timeframe.

International WAAS

Closer to Operational

Implementation

by Mary Ann Davis, GPS TAC/ATO-W Navigation Services

The FAA is working with Canada and

Mexico to extend WAAS service

throughout North America. Work on

this initiative has been underway for

several years, concurrent with WAAS development. Now

this extended capability is one more step closer to reality.

On May 7th, a bilateral international agreement was signed

between the U.S. and Canada outlining cooperative efforts

to extend WAAS service into Canada. A similar agreement

between the U.S. and Mexico is currently pending and expected to receive final signatures shortly.

These agreements outline the cooperative activities necessary to successfully extend WAAS service to Canada and

Mexico. Under the U.S./Canadian agreement, the FAA will

provide four WAAS reference stations (WRS) to NAV

CANADA for installation in Winnipeg, Goose Bay, Gander, and Iqaluit or a mutually agreed to alternate site. These

stations will then be integrated into the operational WAAS.

When this is complete, Canada will gain WAAS operational

capability for a significant portion of its territories. Likewise, the U.S. will receive boosted WAAS coverage for the

northern portion of the U.S. The pending agreement between the U.S. and Mexico is very similar. The FAA plans

to provide five WRSs to Mexico that will then be integrated

into the WAAS. These stations are planned for installation

in Mexico City, Merida, Puerto Vallarta, La Paz, and

Tapachula. When these are integrated into the WAAS,

Mexico will gain WAAS capability in its airspace and the

U.S. will gain better WAAS coverage at its southern borders.

The reference stations for both Canada and Mexico will be

integrated into the WAAS in two phases. The first of these

phases is expected to be complete in 2006. The bilateral

agreements with Canada and Mexico are very significant as

they secure the foundation for WAAS service beyond U.S.

borders.
5

GPS/WAAS Procedures

Data Available on the Web

by Mary Ann Davis, GPS TAC/ATO-W Navigation Services

Did you know that there are over 2500

RNAV approach procedures that can be

used with WAAS? Eleven of these approaches are the new LPV approaches

which can support minimums as low as 250 feet and 3/4

mile (without approach lights) and more are being added with

each procedure publication cycle! Also, did you know that

there over 1400 GPS stand-alone procedures that can be flown

using WAAS? Where can you find more information on these

approach procedures? You can find this information on the

new GPS/WAAS Approaches page on the gps.faa.gov website.

This new page contains a listing of all currently available Lateral Navigation (LNAV) approaches, Lateral Navigation/Vertical Navigation (LNAV/VNAV) approaches, LPV (formerly

Precision Lateral with Vertical) approaches, and GPS standalone. The information for these approaches is contained in

spreadsheets that

can be easily sorted

by state, airport, approach type, and

Part 139 vs. NonPart 139. This information is updated on the

website approximately every 56

days in conjunction with the procedure publication cycle.

Other information contained in this page includes future procedure publication dates and a link to the FAA’s instrument

flight procedures quarterly production schedule. You can find

the GPS/WAAS Approaches page by visiting the gps.faa.gov

website. A button for the GPS/WAAS Approaches page is

available from the front page.

We hope you find this information helpful. Although this

information on the website is updated on a regular basis, there

may be official changes that are put into effect for these approaches prior to the information being updated on the

website. As a result, we ask that you please refer to the latest

approach plates and official flight publication material, and

not this website, when making your flight plans.

WAAS BETA MMR

Contract Signed with

Rockwell

Compiled from information received from manufacturer

The FAA Aviation Systems Standards

(AVN) organization and Rockwell-Collins

have entered into a contract for the WAAS

Beta version Multi-Mode Receiver (MMR)

that allows for WAAS instrument procedure flight inspection

as early as January 2005.

The MMR, a GNLU-930, will be fully certified (black label)

and compliant with the WAAS MOPS, RTCA-229C. This

Beta version consists of a GPS/WAAS sensor that provides

position and integrity data to an integrated navigation system

such as an FMS. The MMR uses Fault Detection and Exclusion (FDE) to provide integrity in the absence of the WAAS

signal.

Rockwell is on track to deliver the first MMR to AVN by November for modification into the Lear 60 fleet. According to

AVN, flight inspection of WAAS procedures (to include LPV

approaches) could start by the beginning of next year.

AVN’s contract with Rockwell could be supplemented for

developing the MMR’s Delta version that provides an “ILS

look-alike” feature.

Formation of the IPCT

by Steve Albers, GPS TAC/ATO-W Navigation Services

The group formerly known as the Satellite Procedures Implementation Team

(SPIT) met April 14-15, 2004 in Arlington, VA. The purpose of the meeting was

to discuss reactivating the group and to decide on the focus

for future work. It was decided that the new team name would

be the Instrument Procedures Coordinating Team (IPCT).
The IPCT is intended to be a “problem identifying” group

and not a “problem solving” group whose focus will be on the

technical aspects of procedure production and implementation. The acting chairperson of the group is Harry Hodges of

AFS-420.

The IPCT is currently drafting a charter and determining its

core membership. A final decision on what organization will

sponsor the group has yet to be made, but the charter will be

approved by the FAA ATO organization. Unless technical

issues arise requiring more frequent meetings, the IPCT plans

to meet quarterly, with the next meeting planned for July 14-

15, 2004 in Arlington, VA. Topics to be discussed include a

34:1 survey issues status report from AFS-420, review of a

strawman issue paper on procedure database coding, WAAS

receiver issues, and a briefing on the LAAS Equipage and

Avionics Pathfinder (LEAP) activities.

Survey Pilot Program - the

Teenage Years

by Tim Roe, GPS TAC/ATO-W Navigation Services

The Survey Pilot Program is maturing

from infancy into its teenage years. As

with any teen this is a turbulent age of

further discovery and yearning to be

grown–up, knowing too much but not really knowing enough.

The program has evolved from infancy with the completion

of the third pilot survey at Stafford Regional Airport. This

survey tested the validity of the new Area Navigation Approach

Precision Conventional (ANA-PC) Landing surface. The selected contractor also provided the team with valuable insight

for FAA Specification 405 and the associated manuals being

developed by National Geodetic Survey (NGS) to support the

program. A key factor identified by the contractor is the need

to clearly identify the aeronautical nuances within the guidance. Items such as defining the airport elevation and how is

it determined, or inquiring why the localizer for Runway 17 is

located at the end of the runway marked Runway 35, may

seem like basic questions to those who work in the aviation

world on a daily basis. However, for the typical land survey

professional these questions could lead to some confusion.

So the team is busily “beefing up” the survey web site with

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new and updated information to fulfill this previously unidentified need.

NGS awarded the contract for a data logger to Abacus Software of Silver Spring, Maryland and they are hard at work

developing this key piece of software for the new survey process. We expect delivery of the system next year and it will be

the final puzzle piece to be put into place. The data logger will

serve as the key communication source between the field crew,

NGS, and the Airports Geographic Information System (GIS).

The team recently briefed the Pilot Survey Program at the

American Association of Airport Executives (AAAE) GIS Subcommittee meeting yielding an excellent response from the

conference attendees. We expect to participate in more user

conferences, such as AOPA’s Fly-in and the AAAE Conference in June, as we continue to get the word out about the

Pilot Survey Program. The next three milestones for the program are completing the Advisory Circulars, completing/updating and validating the web site, and ensuring the appropriate guidance for use of Airport Improvement Program is in

place.

The team is working diligently to integrate the Airports GIS

Data Standard and the Survey Pilot Program requirements,

to ensure that the data collected by the third party surveyors

is the data needed to further the efforts of the Survey Pilot

Program, as well as to support the goals of other FAA lines of

business.

Solar Flares Hit Earth –

WAAS Bends But Does Not

Break

By Tom Dehel, FAA/ATO-P (formerly ACB-430)

At times the Sun launches an attack on

the Earth’s magnetic field and the

earth’s ionosphere. The Wide Area

Augmentation System (WAAS), a space based navigation system, must survive all these blows, and continue to deliver critical navigation services to aviation and other users.
7

There have been stories in the news about satellites that have

become disabled due to the radiation and material blasted

out by the Sun during these rare but severe solar events. However, the WAAS geosynchronous satellites which beam the

WAAS correction messages to Earth, and the Global Positioning System (GPS) satellites which provide the raw ranging signals to users have proved very resistant to this form of solar

attack. In fact, the communications signals themselves are

also only rarely disrupted. In order to understand the relationship between the Sun and WAAS, one needs to understand a very tenuous layer of the Earth’s upper atmosphere

near the edge of space – the ionosphere.

The ionosphere may be thought of as the battleground between WAAS and the Sun. WAAS en route navigation and

non-precision approach services are not affected by disruptions in the ionosphere. These services continued to operate

normally despite recent solar storms. However, an important

service of WAAS - the provision of vertical guidance to allow

Lateral Navigation/Vertical Navigation (LNAV/VNAV) approaches and LPV approaches - can be affected. The reason

these services are affected by the ionosphere is not obvious to

someone who has not had the opportunity to study WAAS,

but the simple explanation goes something like this.

GPS and WAAS fundamentally work by measuring the time

it takes a radio wave to leave a satellite and arrive at the receiver. By using the speed of light, one can turn this time

delay into a distance. If you know where several satellites are,

and you know your distance to those satellites, you can do the

math to compute where you are. BUT, the radio signal is not

always traveling thru the vacuum of space. In our case, it

enters the ionosphere, a rarified but electrically charged medium that can slow the radio signal. This results in the user

receiver determining an incorrect range to the satellites, and,

as a result, the math will give an incorrect position. This error

is small (on the order of tens of meters).

The ionosphere exists every day – atmospheric gases hundreds

of kilometers up in the atmosphere are split into ions and

electrons by radiation from the Sun. This is usually a very

smooth process. The “extra” delay created is about the same,

or rises or declines very smoothly, over distances of thousands

of kilometers. Currently, this error can be reduced and proved

safe for vertically-guided approaches as long as the ionosphere

is in its typical very smooth shape. WAAS, using specialized

receivers at its two dozen reference stations, measures this delay,

and produces an imaginary grid of the ionospheric delay. This

data is sent to users as part of the WAAS message. A civil

aircraft receiver, unable to measure the ionospheric delay itself, simply interpolates the WAAS grid of data to identify

and remove that “extra” delay which would have resulted in

some position error – and thanks to WAAS that error is gone.

However, there is risk to this WAAS ionosphere correction

method if the ionosphere is not “smooth” between the imaginary grid points provided by WAAS. In this case, the interpolation may not be correct. Under the safety constraints of

WAAS, the ionosphere interpolation technique may not be

used if the ionosphere is not proved “smooth”; therefore, any

significant disruptions in the ionosphere above the “normally

smooth” condition is treated as a situation where the safety of

WAAS for vertical guidance cannot be guaranteed. During

these conditions, LNAV/VNAV and LPV approaches are

automatically disabled.

To better understand the effects of solar storms on the ionosphere and on WAAS, let’s look at the storms of 2003 which

took place on October 29, October 30, and November 20.

On these days, an especially energetic group of sunspots (a

magnetic disturbance point on the surface of the Sun), produced very severe X-ray flares, and blasted out billions of tons

of charged material – called a Coronal Mass Ejection. This

material has its own magnetic fields and orientation, and can

either be deflected by the Earth’s magnetic field, or penetrate

and disrupt. On these days, the disruptions were very severe

– classified as the maximum value of 9 on the geomagnetic

Kp scale. They produced several severe “features” and gradients in the ionosphere – good for the advancement of ionospheric studies but bad for aviation users. On these days, the

vertical guidance capability of WAAS, used in LNAV/VNAV

and LPV approaches, was automatically disabled over most of

the country for roughly 6-12 hours each day. This capability

was not disabled because WAAS was not continuing to operate and generating the grid of ionosphere corrections, nor

was there any data proving the corrections were unsafe. This

capability was disabled because the basis of the proof of safety

– that the ionosphere be very smooth – was not being met.

However, WAAS en route and non-precision approach services were completely unaffected – so, WAAS did bend, but it
8

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800 Independence Avenue, SW

Washington, DC 20591

http://gps.faa.gov

Over the next decade, as aviation gradually transitions to an

increased use of WAAS for vertical approaches for more users,

there is also a plan to upgrade the GPS satellites to a second

civil frequency – L5. This will allow the aircraft receiver to

measure the ionospheric delay directly – allowing verticallyguided approaches during even the most severe ionospheric

conditions. At that time, the threat of these solar storms will

become a distant memory.

Storm Enhanced Density (SED) Ionospheric Feature

over Eastern US, Nov. 20, 2003

did not break. Methods are still being studied to mitigate the

effects of these rare events in WAAS, but, in any case, WAAS

continues to meet all current requirements of accuracy, availability and integrity.

The figure below shows the location of a “Storm Enhanced

Density” feature that developed over the Eastern United States

on the afternoon of November 20th. This feature was extremely

un-smooth – basically a narrow structure of ionospheric material extending into space. The plot shows the location of the

highest density of ionospheric material – provided by measurements made by WAAS and National Satellite Test Bed

(NSTB) reference stations as GPS satellites orbited over it.